The present invention relates to a loader of the type for automatic lathes with multiple mandrels.
These loaders generally have a rotary drum supporting a plurality of guides along which are pushed bars to be fed to the multiple mandrels of an automatic lathe. The drum rotates to bring the bars opposite the various machining mandrels in sequence. The drum must be rotated and stopped in the new position with high speed and accuracy. Since the operating speeds of the machines and the masses in play are high the problem of assuring correct braking and stopping is particularly critical. It is noted that in the severest cases the drum must rotate 60.degree. in only 0.2 seconds and then be stopped accurately.
In the prior art it has been proposed to use disc or drum brakes activated by compressed air to stop the inertial movement of the drum. A synchronization mechanism frees the brake during rotation to then reactivate it near the new stopping and machining position. This complicates the structure of the machine and introduces parts subject to wear. In addition, it is always possible for the mechanism to fail in the braking e.g. because of wear, breakage or desynchronization resulting in damage.
The general purpose of the present invention is to obviate the above mentioned drawbacks by making available a simple and surely effective rotary lathe-loader having an innovative braking and positioning device without need of complicated activating devices.